U.S. Pat. No. 2,110,227 described a stretcher with a caster brake system to prevent the stretcher wheels from rolling. This brake system includes a horizontal pipe structure in a rectangular shape with four tire engaging bell-shaped rings at its corners. Cam levers 42 and 43 move the entire rectangular braking structure against the wheels. Because of the long distance; i.e., as much as 5 feet between the front and back casters, any slight longitudinal bend in pipe 38 could cause the bell-shaped rings to fail in engaging the caster wheels. For instance, pipe 38 might be bent when a patient stepped on it to mount the stretcher. Also, the cam levers which are at the side of the stretcher would be difficult for a nurse to get at, particularly when the stretcher was wheeled down a narrow aisle.
Another U.S. Pat. No. 3,304,116 describes a similar system in which all four caster rings are simultaneously urged against the caster wheel by a central longitudinal member which actuates a cam (47 of FIG. 11 ). Here again a bar 36 extends the complete width of the stretcher and any slight bend in this bar could render the brakes ineffective. In this patent, bar 36 is perhaps 2-3 feet long with the cam pressure directly in its center.
In addition to preventing the caster wheels from rolling on the floor, it is also important in certain circumstances to prevent the casters from swiveling. U.S. Pat. No. 1,633,638 describes a spring biased detent system that locks the caster in a particular angular position. However, only a stub lever 17 is provided for actuating the detent system. Thus, a nurse must crawl underneath a stretcher table to lock such caster against swiveling. This caster is not well-suited for a stretcher to which the caster swivel must be frequently locked and unlocked.